In the late 1980s, a new surgical procedure was introduced into the United States to relieve discomfort in those patients with documented signs and symptoms of a condition which has since become known as carpal tunnel syndrome. Carpal tunnel syndrome results from the compression of a person's median nerve. The surgical procedure to relieve carpal tunnel syndrome involves the release of the transverse carpal ligament. Carpal tunnel syndrome is a condition widely occurring in the United States and has become one of the major health and industrial medicine concerns of the 20th century. The loss of wages and time off work have approached hundreds of millions of dollars just in the United States.
As will be appreciated, techniques and devices that can lead to a patient's early return to work, lowered morbidity, and early return of grip strength can have an enormous cost savings for employers, and have significantly gained in popularity in the last few years. One of the main advantages of carpal tunnel release surgery is the ability to perform bilateral medical procedures without the concomitant need for splinting or casting of both arms of the patient, which can lower the total cost of medical care of patients with bilateral carpal tunnel syndrome, representing about 80% of patients with this condition. The cost savings can approach about 40% to about 60% by effecting bilateral carpal tunnel release surgeries, notwithstanding the enormous savings to employers realized by the patient's reduced time away from work and the employers saved benefits concerning workman's compensation.
An essential technique used during carpal tunnel release surgery is one involving arthroscopy. The technique of arthroscopy was initially developed and used for knee surgery procedures in the 1920s. The basic technique for knee arthroscopy has since been applied to shoulder, ankle, wrist, and virtually every other joint in the body. Arthroscopy is generally regarded as a "two-handed" technique.
Dr. James C. Y. Chow has developed a two-portal surgical technique for effecting the release of the transverse carpal ligament. Avoiding human structures such as the superficial palmar arch, the common digital nerve to the third web space, and avoiding the ulnar bursa are requisite to successful release of the transverse carpal ligament. The "Chow technique" facilitates the displacement, to a slight degree, and from the operative field of view, of the ulnar bursa and other human structures that the surgeon would not wish to cut during the carpal tunnel release surgical procedure. Removal of such human structures allows the surgeon to obtain a clearer visual field thus reducing the risk to such human structures when the carpal ligament is released.
A main disadvantage of the "Chow technique" is that this two portal technique involves the risk to adjacent neurovascular structures. Another drawback of the "Chow technique" involves the significant morbidity that a doctor is trying to avoid of a painful palmar incision. Furthermore, the "Chow technique" fails to allow both the displacement from the operative field of those structures the surgeon wishes to avoid cutting simultaneously with the use of surgical instruments for cutting and, thus, effecting the release of the transverse carpal ligament. Accordingly, one medical instrument is inserted to displace the human structures that are not to be cut. After removing the human structures from the operative field of view, that medical instrument is withdrawn and another medical instrument is inserted to cut the ligament. This procedure is repeated as needed during the surgery. Once the retracting medical instrument, commonly known as a probe, is removed from the cannula and prior to the surgical cutting instrument, commonly known as a blade, is replaced into the cannula, the human structures that should not be cut may redisplace back into the operative field of view, thus requiring the surgeon to again insert the probe in an attempt to again remove the human structures from the operative field of view.
Dr. John M. Agee has proposed an endoscopic carpal ligament release surgical approach that attempts to avoid the painful palmar incision inherent with the "Chow technique". The "Agee technique" proposes a single surgical incision in the less painful proximal incision site just proximal to the wrist flexion crease. Dr. Aree further proposes a single hand held device that couples a blade assembly, used to surgically cut the carpal ligament, with an endoscope. Thus, the "Agee technique" advantageously enables a single operator to perform the carpal tunnel release.
Like the "Chow technique", however, one major drawback with the "Agee technique" is the inability of the surgeon to use surgical instruments in both hands. That is, the "Agee technique" does not teach or disclose allowing the surgeon to use both hands during carpal tunnel release surgery in order to push or pull any human structures that may obfuscate or be within the operative field of view while simultaneously using surgical instruments to cut or sever the transverse carpal ligament.
Known carpal tunnel release surgical procedures and those carpal tunnel release devices on the market do not allow the flexibility inherent with traditional arthroscopic surgery to be used to its fullest potential. Known carpal tunnel release surgical procedures and those carpal tunnel release surgical devices that are publicly available do not lend themselves or permit a two-handed surgical technique to be used during carpal tunnel release surgery. That is, no known technique or known device allows a surgeon to use one hand to manipulate one surgical instrument to remove human structures that are not intended to be cut during the procedure from the operative field of view while simultaneously allowing the surgeon to use the other hand to manipulate a second surgical instrument to effectively cut the transverse carpal ligament.
As will be appreciated by those skilled in the art, the carpal canal into which the endoscope is introduced is limited by its transverse cross-sectional area through which pass nine flexor tendons and the median nerve. Thus, the area in which the carpal tunnel release surgery is to be effected is replete with human structures in addition to the transverse carpal ligament that is to be cut during the carpal tunnel release surgical procedure. The most common complications arising from carpal tunnel release surgery involving use of an endoscope concern the risks to the common digital nerve to the third web space being either lacerated, contused or injured, either at the proximal or distal portal with passage of the endoscope.
The Agee device uses a flat-topped surface to enable the operator to push human structures out of the operative field of view of the endoscope. The "Agee technique" and known devices used in combination therewith, however, is not and does not involve a two-handed technique, as traditionally employed in arthroscopy. That is, and while offering an advancement over other techniques, the Agee device does not allow the surgeon to use one hand to manipulate and move human structure other than that to be cut from the operative field of view while allowing the surgeon to use the other hand to cut the transverse carpal tunnel ligament of the carpal canal.
Smith+Nephew Dyonics of Andover, Mass. offers a carpal ligament release system that utilizes two portals, a distinct theoretical disadvantage from a patient's perspective. In the Dyonics system, stability of a surgical cannula is obtained by both a proximal and distal incision. As will be appreciated, any successful carpal tunnel release system must be reasonably stable and yet have flexibility in the depth of cut. The Dyonics System, however, allows only a single operative hand to be used to manipulate an instrument for release of the transverse carpal ligament. The operating surgeon frequently is taught to utilize either a q-tip or nerve hook to try to tease unwanted structures from the operative field, but the simultaneous retraction of the structure while one is cutting is not possible with the Dyonics system. Moreover, the technique of holding the cutting blade in the Dyonics System requires the surgeon to hold the cutting blades in a palm-down, pronated position. This is not a natural surgical technique and must be taught. Allowing the surgeon to hold the knives like one would hold a pencil is a more traditional approach to surgery and one that surgeons are readily familiar with.
As will be appreciated, allowing a surgeon to use both hands during carpal tunnel release surgery while still allowing a traditional approach to surgery would normally appear to have significant drawbacks. That is, since some surgeons are left hand dominant while other surgeons are right hand dominant, some of the carpal tunnel medical instruments must be specifically designed for the right hand dominant surgeons while other carpal tunnel medical instruments must be specifically designed for the left hand dominant surgeons. Thus, and so as to allow a surgeon to feel as comfortable as possible during this relatively delicate surgery, duplicative sets of medical instruments, some configured for right hand dominant surgeons and others configured for left hand dominant surgeons, would appear to be required to perform a two-handed carpal tunnel release surgical technique or approach. Requiring a medical facility, such as a hospital where medical costs are such a serious concern, to carry and inventory duplicate sets or kits of carpal tunnel medical instruments would appear to direct away from the using of a two-handed approach or technique.
Thus, there remains a need and a desire for medical instruments that are flexible enough to allow for two-handed surgical procedures involving the release of the transverse carpal ligament while remaining cost effective.